Problem

How to setup a Mail Relay in Zimbra 8.5?

Solution

Follow the guide below to configure Zimbra 8.5 to use outMail as a Internet Mail Relay. For older versions of Zimbra please see the "How to setup a Mail Relay in Zimbra 8.0.0" article

This article already assumes your Zimbra system is able to send emails externally and that you are already have a terminal connection to your server with the necessary access rights to manage and administor zimbra.

First you need to create a password file for zimbra to use. create a file called /opt/zimbra/conf/relay_password and add the following lines to that file

mxXXXXXX.smtp-engine.com outMail-username:password

Once you have edited the file, a look file needs to be created

postmap /opt/zimbra/conf/relay_password

To enable zimbra to use the outMail service at the prompt type the following

zmprov ms server.domain.com zimbraMtaRelayHost mxXXXXXX.smtp-engine.com

zmprov ms server.domain.com zimbraMtaSmtpSaslPasswordMaps lmdb:/opt/zimbra/conf/relay_password
zmprov ms server.domain.com zimbraMtaSmtpSaslAuthEnable yes
zmprov ms server.domain.com zimbraMtaSmtpCnameOverridesServername no
zmlocalconfig -e postfix_smtp_use_tls=no
zmlocalconfig -e postfix_smtp_sasl_security_options=noanonymous

zmprov ms server.domain.com zimbraMtaSmtpSaslSecurityOptions noanonymous
postconf -e smtp_sasl_mechanism_filter=plain,login
postmap /etc/postfix/relay_passwd 

To enable zimbra to use the outMail with a different SMTP port use the following command line

zmprov ms server.domain.com zimbraMtaRelayHost mxXXXXXX.smtp-engine.com:587

For the above changes to take effect the zimbra service will need restarting (postix reload)